Vim Tips: Map key to shell command

When using Vim, I want to keep keystrokes to a minimum and my focus on the current terminal window. While using Ruby I found that saving a file, flipping to a different terminal window, executing specs and flipping back was taking too much effort.

All the above steps can be solved by simply mapping a keystroke. For example, when in Normal mode I can now save the file and execute RSpec by hitting the comma key.